feat: Namespace autorecognition

There is a way to find the namespace of the controller automatically, instead of calling \Yiisoft\FileRouter\FileRouter::withNamespace.

It costs additional io call, regexp parsing and dependency yiisoft/aliases, but it's good feature not to configure the router.

$controllerDirectory = $this->aliases->get('src') . DIRECTORY_SEPARATOR . $this->baseControllerDirectory;
$classPath = $controllerDirectory . DIRECTORY_SEPARATOR . $directoryPath . DIRECTORY_SEPARATOR . $controller;
$filename = $classPath . '.php';
if (file_exists($filename)) {
    $content = file_get_contents($filename);
    $namespace = preg_match('#namespace\s+(.+?);#', $content, $matches) ? $matches[1] : '';
    if (class_exists($namespace . '\\' . $controller)) {
        return $namespace . '\\' . $controller;
    }
}

Start by reading FileRouter::withNamespace and the router entry points that currently require it, then inspect how the yiisoft/aliases dependency resolves the controller directory. Compare the proposed namespace lookup with the existing routing flow; done means a controller namespace can be detected automatically without calling withNamespace, while preserving explicit configuration.